This invention relates to a fuel delivery rail assembly for an internal combustion engine, especially for an automotive engine, equipped with a fuel injection system. The fuel delivery rail assembly delivers pressurized fuel supplied from a fuel pump toward intake passages or chambers via associated fuel injectors. The assembly is used to simplify installation of the fuel injectors and the fuel supply passages on the engine.
An example of V-type automotive engine equipped with a plurality of fuel injectors is shown in FIG. 5 of the drawings. In this engine, on each side of the crank shaft 40, three cylinders 41 and 42 are located intersecting at a V-shape angle. Toward the interior of intake manifolds 43 and 44, each forming a respective intake passage, pressurized fuel is discharged from fuel injectors 45 and 46. The fuel delivery rail assembly 50, which is the substantial matter of the present invention, comprises an elongated conduit 47 for supplying fuel toward the left-side three cylinders and an elongated conduit 48 for supplying fuel toward the right-side three cylinders 42, both conduits being interconnected for keeping fluid communication therethrough.
In a typical design of a V-6 engine, the fuel delivery rail assembly is constructed in the form as shown in FIG. 1 of the drawings. The fuel delivery rail assembly 20 comprises a pair of conduits 1A and 1B arranged in parallel fashion, both ends of which are interconnected via connecting pipes 4A and 4B. To each one of the conduits 1A and 1B, three sockets 10 are fixed complying with the predetermined mounting orientations so as to receive associated tips of fuel injectors. The axial directions of the sockets should precisely line up in alignment with the respective axial direction of the injectors. Furthermore, pitch lengths between adjacent sockets should precisely coincide with the corresponding pitch lengths between associated injectors. One of the objects of the present invention is directed to these alignment problems as discussed in detail below.
On one hand, at a connection between the connecting pipe 4A and the conduit 1A, a three-way joint 3 is fixed so as to receive a fuel inlet pipe 6, and on the other hand, at a connection between the connecting pipe 4B and the conduit 1B, a three-way joint 5 is fixed so as to receive a fuel return pipe 7.
To the pair of the conduits 1A and 1B, a plurality of thick and rigid brackets 2 are secured bridging the conduits for the purpose of enhancing the rigidity of the fuel delivery pipe assembly while also providing a stable installation to the engine.
In FIG. 4, an example of a conventional connection between a conduit and a socket in the prior art shown. The hollow section of the conduit 1 is generally formed in rectangular cross-section and to the bottom side of the conduit 1 a socket positioning hole 9 is provided. Within the positioning hole 9 a tip of a metallic integral socket 30 is inserted and fixed thereto by means of a brazing connection 36.
The metallic socket 30 is provided with a smooth interior surface 31 for receiving a tip of a fuel injector and an outwardly developing taper surface 32 adjacent its distal end. In particular, the interior surface 31 should be finished extremely smooth in order to establish a complete fluid seal between the surface 31 and a resilient O-ring 39, which is mounted on the injector 45 adapted to be inserted inside the surface 31. Therefore, in manufacturing the socket 30, many kinds of working steps are needed. For example, at first a rough fabrication is made by a forging work, and then it is machined to make a form of the interior surface 31. Finally, the socket is finished with a burnishing machine until the predetermined smoothness is obtained. Under the present situation, making the socket 30 entails many kinds of time-consuming working steps and transferring handling steps, resulting in increased manufacturing cost.
In U.S. Pat. No. 4,286,563 to Fahim et al., issued Sept. 1, 1981, there is disclosed a fuel rail for supplying fuel to a plurality of fuel injectors in a V-type engine. The sockets of the fuel rail are affixed directly to fuel rail means, thereby providing a unitary construction. This invention is directed to a swivel engagement for providing an adjustable alignment between the socket and the injector.
In U.S. Pat. No. 4,457,280 to Hudson, issued Jul. 3, 1984, there is disclosed a fuel injection rail assembly for holding a plurality of electromechanical fuel injector elements in aligned positions on an internal combustion engine. The beam portion of the fuel rail is comprised of two elongated manifold members with overlapping sides brazed together. As a result, the sockets are affixed directly to one of the manifold members. There is a disadvantage that this invention is limited to a simple-formed fuel rail assembly.